Open fireplace installation



July 1, 1947.

Filed March 8, 1944 J. S. HALES ET AL OPEN FIREPLACE INS'IALLATION` 2 Sheets-Sheet l J'ofm S. HnLes Emana MURPHY Lnwnence NAcDvNnLD July 1, 1947. y v J, s, HALES ETAL 2,423,235

OPEN FIREPLACE INSTALLATION Filed March 8, 1944 2 Sheets-Sheet 2 J'aHN S. HALss Enna/vn MURPHY LAwRe/vce MAcpoNALD patented July 1, 14947 OPEN FIREPLACE INSTALLATIGN John Sherwood Hales, Kngstonon-'Ihames, Edmund Murphy, London, and Lawrence Mac- Donald, Ewell, England, assignors to C. U. R. A. Patents Limited, London, England Application March 8, 1944, Serial No. 525,576 In Great Britain February 8, 1943 2 Claims.

The present invention relates to a fireplace construction and `more specifically pertains to open replace installations.

Open fireplace installations are known in which the combustion air supplied to the underside of the grate is derived entirely from outside the room to be heated by the fire, for example from under the floor. Such an arrangement, `as comp-ared with an open replace in which the air for combustion is drawn from inside the room, enables a greater pressure differential across the fuel bed to be obtained. This increased pressure differential can be utilised both to obtain a more rapid stimulation of combustion and to attain a higher rate of combustion.

In the known open fireplace installations of the aforesaid kind, a damper is provided which is intended to control the supply of the air admitted to the underside of the grate from outside the room. It is difficult, however, Ito control the rate of combustion satisfactorily by this means alone. Owing to the relatively high pressure differential across the fuel bed the velocity of the air increases as the damper opening is reduced, and hence the quantity of air admitted in unit time is not reduced in proportion to the reduction in the opening. `Only When the damper is very nearly closed will there be any real reduction in the quantity of air admitted so that it is only possible to obtain any useful variation in the air supply over a very small range of operation of the damper in the vicinity of its closed position.

It is an object of the present invention to provide a more satisfactory control over the rate of combustion.

According to this invention an open fireplace installation comprises, air supply means for the supply of air for combustion from outside the room to be heated by the re, a grate the underside of which receives combustion air entirely from the said air supply means, a chimney disposed above the grate for the removal of products of combustion, a member having an outlet communicating with the said air supply means and so situated near thegrate as to enable air from the said air supply means to pass into the room and thence into the chimney, and valve means provided in the said air supply means for varying the supply of air to the underside of the grate and to said outlet in such manner that when the supply of air tothe underside of the grate is reduced the supply of air to the said outlet is increased and vice versa.

In an installation according to the inventio-n When the valve means, for example a damper,

is operated for the purpose of reducing the supply of air to the underside of the grate an increase in the flow of air through the outlet occurs and this causes a reduction in the pressure differential across the fuel bed; and conversely when the damper or like means is operated for the purpose of increasing the supply of air to the underside of the grate a reduction in the ow of air through the outlet occurs causing an increase in the pressure differential across the fuel bed.

Owing to the variation in the pressure differen tal which accompanies the operation of the valve means a more satisfactory control of the quantity of air admitted to the underside of the grate, and consequently of the rate of combustion, is obtained.

The outlet to enable air from the said air supply means to pass into the room and thence into the chimney may advantageously be situated in front of and near the grate.

The air may be derived from outside the room in any suitable manner, but it is generally more convenient to derive it from the space beneath the floor ofthe room.

The invention is illustrated in the accompanying drawings, in which Figure 1 shows a vertical cross sectional view of one construction of open fireplace installation in accordance with the invention, and Figure 2 is a similar View of the same construction drawn on a smaller scale to include the chimney.

The fireplace installation shown in the drawings has a hearth l raised above the level of the door 2. The grate 3 is situated at about the level of the hearth, and an outlet is provided in the hearth in the form of an opening in which is supported a removable cover plate 4 provided with a grille or louvred opening lla to permit air to pass through the plate 4 from beneath the oor. A cavity or chamber 5 is provided beneath the fireplace extending from the back of the grate to the front edge of .the opening in the hearth. An opening 6 to admit air from beneath the floor is provided at the top of the front wall l of the cavity 5.

At the rear edge of the plate 4 is pivoted at 8 a damper plate 9 extending beneath the grille or louvred opening 4a. The damper plate 9 is adapted in its lowermost position to close an inlet lli in an inclined frame I l, which frame shuts off communication between the cavity 5 and the opening 6 Yexcept through the inlet ID. In its uppermost position the upper surface of the damper plate 9 rests against the underside of the cover plate 4 and closes the louvred opening 4a.

The movement oi the damper plate 9 is con trolled by the rotation of a knob I2 iixed to a spindle I3 rotatably mounted in a boss I4 on the plate Il. At its lower end the spindle I3 carries a lug I upon which rests a helical ramp t6 on the underside of the damper plate 9". The pitch of the ramp IB is suchthat a sing-le revolution of the spindle vI3 and its lug I5 will suice to move the damper plate 9 from either of its extreme positions to the other, and that the damper plate will be held in any intermediate position bythe lug. In the lowermost position of the damper plate the air supply from the opening Sjt'o the cavity 5 and underside of the grate 3 is shut on, and 'the'air supply from the opening S to the louvred opening 6a fully open. Conversely, in the uppermost position of the damper plate 9 the air/supply to the louvred opening 4a. is shut oii, and the air supply to the cavity 5 and grate 3 is fully open. At intermediate positions of the damper plate 9 a part oi. the air from the opening S, passes to the cavity aandfg'rate '3 and "a paltto 'the 'lcuvred open-v ifigllc.' i

The' cavity accommcolates an ash receiver li dispc'ised4 ben'ea'tlfi the grate. The' n capacity of. ythe ash receiver is preferably` suiciently large to receiveA the ash produced by the lire 4Vover a period oseveral days, vexam'pl'e'a"week.` When' it is necessary'to empty 'theu ash receiver, the plate E. covering 'the lopeningy -inthe'hear'th is removed, ai, fi-.eeh riceve is the, moved mais. beneat-,hv theA inlet liln and lifted through it and tholigh' he opening. inthe, hearthT The rateef Combustion Qf. the vfire iswntrelled by manipulating the. damper. plate 8.-, When the. latter is in its uppermost position al1 or substan telly all the air drawn throes-h .the @perline 6 from outside vthe room passes through the inlet I0 and tothe underside lof the grate, andrull advantage is taken of the high pressurediferentia'l thus obtained. In consequence t-he stimulation of combustion is` very rapid4 and combustion lcan attain a very high rate. For example, vin a fireplace of average size a rate of .combustion as high as 8 lbs. of bituminous coaljper hour `can be attained as compared with arateoijl lbs. per heur in the caseof an ordinary open'r'e.

ltwill, however, `seldom be 'desiredto maintain high rates offcombustion Afor Vlong periods, `so that the'up'perinost position of the 'damper .plate "9 will generally be used only to produce rapid acceleration of combustion. When the' damper plate is 'in Lits lowermost .position all or substantially 'all 'the airdrawn through the opening 6 from loutside the'room passes through the ilouvred opening'li'a in vthe 'hearth into @their-oom and thence intoth'e chimney '118, Y'and the rate of combustion is then-'reducedt'oits lowest leveLltor example, to about' l lb. of 'coal Y'per lh'our or less. VIn order to adj-ust the ratejof"combustion vto a value Ybetween these'twoextremes the damperplate'is set atan ihterm'ed-iate position -a't which -theratio vof the air` passing to the `underside ofthe 'grate 3 to 4the air passing `tl'irough'tl'ie louvred opening 4a infthe hearth is such as tov give the desired rate'of'lcoinbutton.

kWith anope'n' fireplace installationjconstructed ih accordance wit'hthe invention *it is possible to burnfsatisfactorily fuels "such as anthracite =and coke, whichare fdifcult ito 'burn alone v`in 'anfopen iiifeplace in 'which'the` air for combustionis drawn yfromwithin the room. For 'the same reason `'t istposjsible rto burn bituminous jcoaI of Vsmall sizes wnicnpwing to 'their s1owcombusticn-rate 'are not usually regarded as suitable for open iireplaces of the ordinary type.

A further advantage of an open fireplace installation constructed in accordance with the invention is that it becomes possible, at medium rates of combustion, materially to reduce the quantity of air drawn into the room through doors, windows or other apertures.

It will be understood that the invention may be applied to open replace installations having l associated therewith an appliance heated by the nre, such as a boiler or cooking oven.

Owing to the rapid acceleration in the rate of combustion obtainable in an open fireplace installation in accordance with the invention, the time taken, when the fire is initially lighted or when the re is refuelled, for the fuel bed to reach a suiiiciently high temperature to enable the volatile products such as smoke to be burned is considerably reduced as compared with the time required in an ordinary open fire.

We' claim:

1 An 'open iireplace installation comprising, airV supply means for the supply'of air orcomloustion from outside the room to 'be' heated by the lire, a grate the underside ofrwhich' receives combustion air entirely from the said air supply means', a' chimney disposed. above the grateior the' removal oi products of combustion, a member having an 'outlet communicating with the said air supply means and so `situated in ront'o'a'nd near the grate as to enable 'air from the saidair supply means to pass into the'room and thence into lthe chimney, and valve means provi'ded'in the' said air supply means f-or varying 'the supply' of air to the underside of the grateand'tosaid outlet in such manner that when the 'si-ipp'ly of air to the underside of the grate lis reduced the supply of air to the said `outlet is increased and `vvice versa. A

2. An open replace installation comprising, 'a grate, 'a' chimney disposed above" they grate, "air supply means' for the :supply -dgf fair forcor'nfbu'stion from -a space beneath thefioor "of the room't be heated by the lire', la member having -anoutl'et l situated in Ytrent df and 'near vthegiate to admit a'i-r from the said lair vsupt'ily'meal-ns int-o the `said room and thence into the chimney, side fand bottom walls formin'g'below the floor of the'said room a 'chamber having at the front part ofthe top' thereof beneath -the lsaid ou'tle't member anfinlet to admit 'lair to the -chamfber fromrv the said `v`air supplymea'ns, 'the said-grate being inountedfove'r thelrear part ofthe topof the said "chamber :so that the underside'of the grate -recivescombus'- tionl air entirely from the said chamberffanda damper plate adjustablyv mounted between4 Ithe said inlet -and :outlet for varying 4.the supply -of lair thereto 1in -such vmanner v'that when the supply ito the inlet is reduced lthe 'supply'to Ithe -outl'et Iis increased and'vioe versa. JOHN 'SH-ERWOOD EDM-UND MURPHY. j'

LAWRENCE MACDONALD.

rihe -ifollowin'g references are -of 'record in the file of this patent: Y

UNITED. SsATES .Passare Number :Name Date .5,1158 Sexton.' yJune 19, 118.47 `1 48,567 `Kendrick :Man '1'7, 118.7 .4 795,226 Jensen .Jul-374128,' w05 "(O'therireerens. Onlfpllewing page) Number UNITED STATES PATENTS Name Date Merrick Apr. 12, 1881 Risdon Dec. 30, 1930 Humphreys Mar. 2, 1897 Murdoch May 2, 1882 Robinson Oct. 28, 1884 Number FOREIGN PA'IENTS Country Date Great Britain 1910 Great Britain 1861 Great Britain 1843 Great Britain 1887 Great Britain 1909 Great Britain Feb. 28, 1924 Great Britain Nov. 24,1939 

